There are numerous industries today where it is desirable to filter contaminating particles from a liquid and particle mixture that has been produced during a manufacturing process. For example, in the papermaking industry it is often necessary to separate pulp fibers from water and other liquid chemicals. Similarly, in the textile industry, lint collected during the manufacturing process in water or other liquid utilized in the process must often be removed. There are a variety of reasons for the separation process. For example, it may be desirable to reuse the liquid portion of the mixture. Also, it may be desirable to collect the particle material for various additional manufacturing steps or reuse.
A conventional way of accomplishing the filtering operation is to utilize a vertical tank with an inlet at the top, an outlet intermediate the top and the bottom and a vertically mounted filter medium on the interior of the tank. Space is provided between the vertical filter and the inner wall of the tank and a drainage or dump opening is at the bottom of the tank. The drainage opening is normally closed during the filtering operation and is opened to periodically dump the collected particles. In operation of this type of system, the mixture of particles and liquid is introduced through the inlet opening into the vertical chamber formed between the outer wall of the filter and inner side wall of the tank. The mixture attempts to work its way through the filter to the central portion of the tank with the particles being filtered out and retained between the filter and the inner wall of the tank. Periodically, the tank is open and drained or dumped to rid the filtering structure of accumulated particles. In the meanwhile during operation, the liquid which is separated from the particles by the filter passes to an outlet for collection. The difficulty that arises with this type of a system is that the mixture engaging the filter surface is directed with such force against the mesh surface that the particles clog the apertures in the mesh. This initially makes the filter less efficient and ultimately precludes all further filtering action. At that point, the filter system must be opened and the filter removed and cleaned or replaced.
Attempts at increasing the velocity of the mixture entering the tank and engaging the filter surface have been unsuccessful in alleviating this problem. An opposite result occurs in that the particles are more tightly wedged or packed into the aperture of the filter. Lessening the velocity also has proved to be ineffectual. The result is that the particles still tend to congregate or migrate into one small area of the filter, for example, a portion of the narrow chamber between the filter and the inner wall of the tank, thereby clogging the filter and requiring that the filter be periodically removed and cleaned or replaced.
Thus, the shortcomings of existing filtering systems are readily apparent. The improvement of the present invention is a significant step forward in the art.